Nanotubes may be fabricated using a variety of approaches. For example, nanotubes can be produced by conducting chemical vapor deposition (CVD) in such a manner that the nanotubes can be caused to deposit either on a moving belt or cylinder, where the nanotubes consolidate so as to form a non-woven sheet. Alternatively, the nanotubes can be taken up by a spinning device and spun into a yarn. Nanotubes collected as yarns, non-woven sheets, or similar extensible structures can also be fabricated by other means. For instance, the nanotubes can be dispersed in a water surfactant solution, then caused to precipitate onto a filter drum or membrane, where they can be subsequently be dried and removed as a sort of paper. Similarly, nanotubes collected as yarns can also be produced from solutions, and is well known in the art. In general, the nanotubes produced within these extensible structures can be either single-walled (SWNT) or multi-walled (MWNT), and may be made from, for example, carbon, boron, or a combination thereof.
Due to the random nature of the growth and fabrication process, as well as the collection process, the texture, along with the position of the nanotubes relative to adjacent nanotubes within the extensible structure may also be random. In other words, the nanotubes within these extensible structures may not be well aligned, particularly for the non-woven sheets.
Since there are certain physical and mechanical properties that are dependent on alignment, the random nature of the nanotubes within these extensible structures can affect the properties of these extensible structures. The properties that may be affected include tensile strength and modulus, electrical conductivity, thermal conductivity, Seebeck coefficient, Peltier coefficient, and density. Other properties which may be affected, include the complex index of refraction, the frequency dependency of resistivity, and chemical reactivity.
To address the nanotube alignment issue prior to the formation of the extensible structure can be cumbersome, expensive, and cost prohibitive in connection with the fabrication process.
Accordingly, it would be desirable to provide a process which can enhance nanotube alignment within an extensible structure, while being economical, subsequent to the formation of the extensible structure.